The present invention relates to an image sensor and, for example, to an image sensor with phase detection autofocus feature.
An imaging device such as a camera uses a CCD or CMOS sensor as an image sensor and outputs an image obtained by the image sensor as photographed data. Such an imaging device is often equipped with autofocus feature that automatically enhances the sharpness of an image taken. One technique to implement the autofocus is phase detection autofocus.
In phase detection autofocus, one pair or two pairs of photoreceptors are placed for each of microlenses arranged two-dimensionally, and light of the photoreceptors is projected on the pupil of the imaging optical system using the microlens to thereby divide the pupil. In phase detection autofocus, object images are formed using two light beams that have passed through different parts of the pupil of the imaging optical system, and a positional phase difference between the two object images is detected based on the output of the image sensor and converted into the amount of defocus of the imaging optical system. An example of the imaging device with phase detection autofocus feature as described above is disclosed in Japanese Patent No. 3774597.